.\"	$OpenBSD: ieee80211_node.9,v 1.7 2013/07/17 20:21:53 schwarze Exp $
.\"
.\" Copyright (c) 2004 Bruce M. Simpson <bms@spc.org>
.\" Copyright (c) 2004 Darron Broad <darron@kewl.org>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
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.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" $FreeBSD: src/share/man/man9/ieee80211_node.9,v 1.3 2004/07/07 12:59:39 ru Exp $
.\" $Id: ieee80211_node.9,v 1.7 2013/07/17 20:21:53 schwarze Exp $
.\"
.Dd $Mdocdate: July 17 2013 $
.Dt IEEE80211_NODE 9
.Os
.Sh NAME
.Nm ieee80211_node_attach ,
.Nm ieee80211_node_lateattach ,
.Nm ieee80211_node_detach ,
.Nm ieee80211_begin_scan ,
.Nm ieee80211_next_scan ,
.Nm ieee80211_create_ibss ,
.Nm ieee80211_end_scan ,
.Nm ieee80211_alloc_node ,
.Nm ieee80211_dup_bss ,
.Nm ieee80211_find_node ,
.Nm ieee80211_release_node ,
.Nm ieee80211_free_node ,
.Nm ieee80211_free_allnodes ,
.Nm ieee80211_iterate_nodes
.Nd software 802.11 stack node management functions
.Sh SYNOPSIS
.In net80211/ieee80211_var.h
.In net80211/ieee80211_proto.h
.In net80211/ieee80211_node.h
.Ft void
.Fn ieee80211_node_attach "struct ifnet *ifp"
.Ft void
.Fn ieee80211_node_lateattach "struct ifnet *ifp"
.Ft void
.Fn ieee80211_node_detach "struct ifnet *ifp"
.Ft void
.Fn ieee80211_begin_scan "struct ifnet *ifp"
.Ft void
.Fn ieee80211_next_scan "struct ifnet *ifp"
.Ft void
.Fo ieee80211_create_ibss
.Fa "struct ieee80211com *ic" "struct ieee80211_channel *chan"
.Fc
.Ft void
.Fn ieee80211_end_scan "struct ifnet *ifp"
.Ft struct ieee80211_node *
.Fn ieee80211_alloc_node "struct ieee80211com *ic" "const u_int8_t *macaddr"
.Ft struct ieee80211_node *
.Fn ieee80211_dup_bss "struct ieee80211com *ic" "const u_int8_t *macaddr"
.Ft struct ieee80211_node *
.Fn ieee80211_find_node "struct ieee80211com *ic" "const u_int8_t *macaddr"
.Ft struct ieee80211_node *
.Ft void
.Fn ieee80211_release_node "struct ieee80211com *ic" "struct ieee80211_node *ni"
.Ft void
.Fn ieee80211_free_node "struct ieee80211com *ic" "struct ieee80211_node *ni"
.Ft void
.Fn ieee80211_free_allnodes "struct ieee80211com *ic"
.Ft void
.Fo ieee80211_iterate_nodes
.Fa "struct ieee80211com *ic" "ieee80211_iter_func *f" "void *arg"
.Fc
.Sh DESCRIPTION
These functions are used to manage node lists within the software
802.11 stack.
These lists are typically used for implementing host-mode AP functionality,
or providing signal quality information about neighbouring nodes.
.Pp
.\"
The
.Fn ieee80211_node_attach
function is called from
.Xr ieee80211_ifattach 9
to initialize node database management callbacks for the interface
.Fa ifp
(specifically for memory allocation, node copying and node
signal inspection).
These functions may be overridden in special circumstances,
as long as this is done after calling
.Xr ieee80211_ifattach 9
and prior to any other call which may allocate a node.
.Pp
.\"
The
.Fn ieee80211_node_lateattach
function initialises the
.Va ic_bss
node element of the interface
.Fa ifp
during
.Xr ieee80211_media_init 9 .
This late attachment is to account for certain special cases described under
.Fn ieee80211_node_attach .
.Pp
.\"
The
.Fn ieee80211_node_detach
function destroys all node database state associated with the interface
.Fa ifp ,
and is usually called during device detach.
.Pp
.\"
The
.Fn ieee80211_begin_scan
function initialises the node database in preparation of an active
scan for an access point on the interface
.Fa ifp .
The scan begins on the next radio channel by calling
.Fn ieee80211_next_scan
internally.
The actual scanning for an access point is not automated;
the device driver itself only handles setting the radio frequency
of the card and stepping through the channels.
.Pp
.\"
The
.Fn ieee80211_next_scan
function is used to inform the
.Xr ieee80211 9
layer that the interface
.Fa ifp
is now scanning for an access point on the next radio channel.
A device driver is expected to first call
.Fn ieee80211_begin_scan ,
to initialize the node database,
then set the radio channel on the device;
then, after a certain time has elapsed (200ms for example), call
.Fn ieee80211_next_scan
to move to the next channel.
Typically, a timeout is used to automate this process; see
.Xr timeout 9
for more information on how to use timeouts.
.Pp
.\"
The
.Fn ieee80211_create_ibss
function sets up the net80211-specific portion of an interface's softc,
.Fa ic ,
for use in IBSS mode.
.Pp
.\"
The
.Fn ieee80211_end_scan
function is called by
.Fn ieee80211_next_scan
when the state machine has performed a full cycle of scanning on
all available radio channels.
Internally,
.Fn ieee80211_end_scan
will inspect the node cache associated with the interface
.Fa ifp
for suitable access points found during scanning, and associate with one,
should the parameters of the node match those of the configuration
requested from userland.
.Pp
.\"
The
.Fn ieee80211_alloc_node
function allocates an instance of
.Vt "struct ieee80211_node"
for a node having the MAC address
.Fa macaddr ,
and associates it with the interface
.Fa ic .
If the allocation is successful, the node structure is initialised by
.Fn ieee80211_setup_node ;
otherwise,
.Dv NULL
is returned.
.Pp
.\"
The
.Fn ieee80211_dup_bss
function is similar to
.Fn ieee80211_alloc_node ,
but is instead used to create a node database entry for the BSSID
.Fa macaddr
associated with the interface
.Fa ic .
If the allocation is successful, the node structure is initialised by
.Fn ieee80211_setup_node ;
otherwise,
.Dv NULL
is returned.
.Pp
.\"
The
.Fn ieee80211_find_node
function will iterate through the node list associated with the interface
.Fa ic ,
searching for a node entry which matches
.Fa macaddr .
If the entry is found, its reference count is incremented, and
a pointer to the node is returned; otherwise,
.Dv NULL
will be returned.
.Pp
.\"
The
.Fn ieee80211_free_node
function will remove the node
.Fa ni
from the node database entries associated with the interface
.Fa ic ,
and free any memory associated with the node.
This private method can be overridden in
.Fn ieee80211_node_attach .
.\"
.Pp
The
.Fn ieee80211_free_allnodes
function will iterate through the node list calling
.Fn ieee80211_free_node
for all nodes associated with the interface
.Fa ic .
.Pp
.\"
The
.Fn ieee80211_iterate_nodes
function will call the user-defined callback function
.Fa f
for all nodes in the node database associated with the interface
.Fa ic .
The callback is invoked with the with the user-supplied value
.Fa arg
and a pointer to the current node.
.\"
.Sh SEE ALSO
.Xr ieee80211 9
.Sh HISTORY
The
.Nm ieee80211
series of functions first appeared in
.Nx 1.5 ,
and were later ported to
.Fx 4.6
and
.Ox 3.6 .
.Sh AUTHORS
.An -nosplit
This man page was written by
.An Bruce M. Simpson Aq Mt bms@FreeBSD.org
and
.An Darron Broad Aq Mt darron@kewl.org .
